{
语法百题 解题报告：
 http://git.oschina.net/et0662/sznoi-grammar/ 
}
var
	n,s,i,start,t,max:longint;
begin
	max:=0;
	read(n,s);
	for i:=1 to n do
	begin
		read(start,t);
		t:=start+s div t;
		if(max<t) then max:=t;
	end;
	writeln(max);
end.
